Epilepsy, one of the most prevalent chronic neurological diseases, affects approximately 0.6-1% of the general population, representing an economic burden of 0.1-1% of the total budget of health care systems in some parts of the world, and a significant proportion of these costs can be attributed to the way in which epilepsy is diagnosed. Epilepsy is characterized by the predisposition to develop spontaneous unprovoked seizures (epileptogenicity). Presently, the diagnosis of epilepsy relies on a patient's clinical history and is based on identifying surrogate markers for epileptogenicity such as the presence of repeated seizures. Seizures are the response of the brain to multiple factors, including internal dynamical tendency or “epileptogenicity level”, environmental factors and triggering mechanisms. Seizures can occur in any brain, including apparently normal brains, if the appropriate stimulus is applied. Stimuli that can evoke seizures include hyperventilation, electroshock and photo stimulation. Because of their unpredictable nature, seizures are often difficult to observe while a patient is in the clinic, and this inability to observe seizures in a timely manner often leads to a delay in the diagnosis of patients with epilepsy, which in turn delays treatment for the patient. Clinical events that are suggestive of seizures are confirmed with the concomitant electroencephalogram (EEG) recording that demonstrates their epileptic nature.
One of the most frequent epilepsy syndromes are idiopathic generalized epilepsies, and among them childhood and adolescence absence epilepsy. In these patients, no tangible structural brain abnormality is present on available brain imaging and structural MRI brain images are usually normal or similar to those patients without epilepsy. The diagnosis in absence epilepsy can be easily obtained by recording absence seizures even on routine EEG, therefore confirming the diagnosis by recorded EEG seizures. Additionally, these patients usually do not have any other obvious structural brain changes that can be detected easily with current structural brain imaging techniques. Therefore, this patient population is an ideal group to analyze brain changes related to epilepsy without confounding structural brain changes.